We propose to investigate whether an elevation in body temperature coupled with the normally observed changes in plasma concentration of trace metals constitute a coordinated host defense response in bacterially infected reptiles and mammals. The work with reptiles will initially involve a description of the changes in plasma concentrations of zinc and copper during infection with Aeromonas hydrophila, a gram-negative bacterium pathogenic to reptiles. Assuming there is a change in these trace metals during infection, then the effects of growing these bacteria in media containing various concentrations of these trace metals and at febrile and afebrile temperatures will be determined. The work with mammals will involve investigating the effects of growing Pasteurella multocida, a gram-negative bacterium pathogenic to rabbits, in plasma from noninfected and infected rabbits and at febrile and afebrile temperatures to determine whether an elevation in temperature, coupled with the changes known to occur in the plasma levels of these trace metals could have any effect on the growth of these pathogenic bacteria. In later studies we propose to investigate the effects of changing the concentrations of copper and zinc in the growth media on the in vitro growth rate of P. multocida at afebrile and febrile temperatures.